Risk analysis of reservoir floodwater utilization coupling meteorological and hydrological uncertainties
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ORIGINAL PAPER
Risk analysis of reservoir floodwater utilization coupling meteorological and hydrological uncertainties Qingwen Lu1 • Ping-an Zhong1,2 • Bin Xu1 • Feilin Zhu1 • Han Wang1 • Yufei Ma1
Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Dynamic control of flood-limited water level (FLWL) is an effective method to realize floodwater utilization, which can alleviate the contradiction between flood control and conservation during flood seasons. In this study, a method of identifying upper bound of FLWL is presented simultaneously considering pre-release for water supply in rainless period and pre-release for flood control in the early period of flood. A risk analysis framework considering continuous rainless-day forecast error and flood forecast error is established. An improved truncated Gaussian distribution to describe rainless-day forecast error is proposed, combined with normal distribution describing flood forecast error to derive the distribution of excess storage determined by the method of pre-release based on forecasts. Then risk assessment and decision making are conducted. The Xianghongdian Reservoir is selected for a case study. The results indicate that the allowable excess storage can be determined under a given acceptable risk by using this analytical method. Moreover, the excess storage decreases with the safety margin reserved for the downstream increasing under the same acceptable risk. Keywords Reservoir Dynamic control of flood-limited water level Uncertainty Risk analysis
1 Introduction Reservoirs are mainly designed and operated for both flood control and water conservation. However, there is a conflict between flood control safety and economic benefits due to the limit of reservoir storage capacity (Krzysztofowicz and Duckstein 1979; Rani and Moreira 2010). Flood control needs more empty storage to accommodate an impending flood, but water conservation needs greater amount of stored-water for irrigation, recreation, and hydropower generation. The flood-limited water level (FLWL) is the key parameter to coordinate the contradiction between flood control and water conservation (Duren and Beard 1972; Jain et al. 1992; Yun and Singh 2008; Li et al. 2010; Zhang et al. 2018). Traditionally, the reservoir water & Ping-an Zhong [email protected] 1
College of Hydrology and Water Resources, Hohai University, Xikang Road, Nanjing 210098, China
2
National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Xikang Road, Nanjing 210098, China
storage is controlled below the FLWL to prevent small probability events such as design flood or check flood during the entire flood season. This operation mode is called the static control of FLWL (SC-FLWL). Although SC-FLWL ensures the flood control safety to some extent, it is likely that there will be no water to be stored after the flood, which affects the water conservation benefit (Windsor 1973; Wang and Zhou 2006; Peng et al. 2017). Therefore, some scholars
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